Presence and Maturation Dynamics of Mandibular Third Molars and Their Influence on Late Mandibular Incisor Crowding: A Longitudinal Study

Factors associated with indication of prophylactic extraction of the lower third molar in orthodontic practice

Background

To date, there is no consensus on the factors that influence on indication for prophylactic extraction of the third molar, however it is a common indication in orthodontics. Aim: To determine the factors associated with indication of prophylactic extraction of the lower third molar in orthodontic practice.

Material and Methods

This cross-sectional analytical study used an online survey to obtain responses from 100 professionals with clinical practice in orthodontics. The Survey Monkey software was used to enter a valid and reliable questionnaire of 11 questions to obtain demographic and clinical information of the professional, as well as some patient conditions that could be considered in a possible indication for prophylactic extraction. The questionnaire was sent through social networks and instant messaging applications. Chi Square test was used to evaluate associated factors and binomial logistic regression to identify risk or protective factors.

Results

Factors significantly associated with indication of prophylactic extraction of the lower third molar were experience in orthodontics (p-value = 0.060; OR=0.325), characteristics of impaction (p-value = 0.012; OR=3.689), prevention of pericoronitis (p-value = 0.014; OR=3.769) and help stability of treatment results (p-value = 0.002; OR=6.074).

Conclusions

The risk factors to indication for prophylactic extraction of the lower third molar were impaction of the third molar, prevention of pericoronitis and helping the stability of the results after treatment. Furthermore, experience in orthodontics was identified as a protective factor for this indication. Key words:Orthodontics, risk factors, third molar, tooth extraction.

Effect of mandibular third molars on crowding of mandibular teeth in patients with or without previous orthodontic treatment: a systematic review and meta-analysis

OBJECTIVES

To assess the scientific evidence related to the role of the mandibular third molars on the late crowding of the lower anterior teeth in patients with or without previous orthodontic treatment. The secondary outcomes included changes in mandibular arch width and arch length.

MATERIALS AND METHODS

The databases PubMed, Scopus, ProQuest, and Google Scholar were searched from inception until April 2022. The included papers were studies evaluating the role of mandibular third molars on crowding of mandibular anterior teeth in patients of any age and gender, with mandibular third molars impacted or semi-impacted or erupted. Predetermined and prepiloted data collection forms were used to record the necessary information.

RESULTS

Thirteen observational studies were included in the present systematic review. Most of them were assigned an overall risk of bias of moderate risk while the rest of them were at high risk. Four studies found an association between the presence of mandibular third molar and mandibular incisor crowding. Finally, seven studies were included in the quantitative analysis. Three different meta-analyses were conducted: for patients (a) with or (b) without previous orthodontic treatment and (c) in combination for patients with and without previous orthodontic treatment. According to the pooled results of all three meta-analyses, random effects model yielded a significant benefit for those without third molars compared to those with third molars regarding crowding, mean Little's irregularity index and mean arch length.

CONCLUSIONS

Lower third molars may contribute to mandibular crowding and lower arch constriction. Further prospective research of high quality is needed to clarify the impact of third molars on anterior mandibular crowding.

Dentists' perception of third molar surgery in the Kingdom of Saudi Arabia: A cross sectional pilot study

Background/purpose

Concerns about the indications for the surgical removal of third molars have not yet reached a decisive agreement. The aim of the study was to evaluate the perception and practice of Saudi' dentists when encountering third molars clinical situations including diagnosis, treatment, and postsurgical care.

Materials and methods

A cross-sectional survey was conducted and approved by the ethics research committee at Prince Sattam Bin Abdulaziz (PSAU). The survey comprised of four sets of questions with multiple-choice answers including the participants' details and type of practice (private or government), clinical awareness and attitude regarding lower third molars surgery, and the confidence level of dentists when performing third molars extraction. The survey was published online with a timeframe of three months to respond.

Results

196 participants responded to the designated survey (55 dental interns and 141 general dental practitioners (GPs)). Most responses (80.1%) were from Riyadh province (central region). There was a significant difference between GPs and interns in terms of impacted third molars with associated cystic lesions, bony impactions, and diffuse pain (P < 0.05). Male dentists tend to prescribe antibiotics more than female dentists (P = 0.001) and GPs more than interns (P = 0.027). The results also indicated that male dentists were more confident than females when performing third molar extraction. Generally, female dentists preferred to have further training on such surgery (P < 0.05).

Conclusion

Continuing professional development programs both during dental internship and general practice are recommended to improve the required skills of third molar extraction.

Three-dimensional relationship between the degree of bilateral impacted mandibular third molars angulation and the mandibular dental arch parameters: a cross-sectional comparative study

OBJECTIVE

The purpose of this study was to three-dimensionally evaluate the relationship between the degree of bilateral impacted mandibular third molar (IM3M) angulation and the mandibular dental arch parameters in normal skeletal and dental malocclusion patients.

MATERIALS AND METHODS

In this retrospective cross-sectional comparative study, 120 adult subjects' cone-beam computed tomography (CBCT) images were three-dimensionally analyzed. The sample included 120 adults aged 20-30 years, with a gender distribution of 51 male and 69 female participants. The sample was divided into 100 adults with bilateral IM3M (study group) and 20 adults with normal bilateral erupted M3M (control group). The study group was sub-divided into three groups according to the degree of IM3M buccolingual angulation (BL°): group A, < 12° on the center of the ridge (N = 30), group B, 12-24° off-center of the ridge (N = 40), group C, > 24° off-center of the ridge (N = 30). The study group was also sub-divided into two groups according to IM3M mesiodistal angulation (MD°): group 1 from 10 to 45° (N = 36), group 2 > 45° (N = 64). Comparison within and between groups was performed using one-way ANOVA followed by Tukey's post hoc test. The correlation between IM3M, BL, and MD angulation and the mandibular arch parameter was calculated using Pearson's correlation coefficient.

RESULTS

Statistically significant differences (P < 0.001) were found between the IM3M BL° and anterior teeth inclination, arch length (AL), and inter-second molar width (inter 2nd MW) as well as between the IM3M MD° with anterior crowding and the arch length (P < 0.001). A significant positive correlation was found between IM3M BL° and anterior teeth inclination and between IM3M MD° and anterior teeth crowding and inter 2nd MW. A significant negative correlation was observed between IM3M BL° and inter 1st MW and 2nd MW.

CONCLUSION

The degree of buccolingual and mesiodistal angulation of the impacted mandibular third molars was related with mandibular dentoalveolar changes. Increased buccolingual angulation is generally associated with increased anterior teeth inclination and decreased 1st and 2nd inter-molar width. The increase in mesiodistal angulations was generally related with increased anterior teeth crowding and 2nd inter-molar width.

CLINICAL RELEVANCE

Assessment of the relationship between the impacted mandibular third molars and the degree of arch discrepancy, and the position of mandibular incisors in the three planes of space might help in the decision-making process for the extraction of the impacted third molars in adult patients.